To use S355 steel plate for offshore applications, a full qualification is needed according to the appropriate standard EN 10225:2009. This standard specifies a whole host of investigations to be performed, from welding with pre-defined heat input levels and full testing of the welds to specific tests to assess the hardenability and cold cracking sensitivity.
Cost reduction is an important topic in the offshore wind sector. However, in view of the move to larger turbine sizes and deeper waters, costs of foundation structures will rise. It is now possible to test tubular joints having the dimensions of offshore wind turbine jacket structures at millions of cycles within a week and with low energy consumption.
As threaded connections are submitted to variable loading they can suffer from fatigue. The critical locations for fatigue were determined and confirmed by experiments. The large scale resonant bending test proved to be valuable test equipment.